Universität Stuttgart

Permanent URI for this communityhttps://elib.uni-stuttgart.de/handle/11682/1

Browse

Author: search.filters.author.Zander, ChristianSubject: search.filters.subject.540

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Wall layer formation in continuously operated tubular reactors for free‐radical polymerizations
    (2023) Welzel, Stefan; Zander, Christian; Nieken, Ulrich
    Polymer fouling is a major problem for the operation of continuous reactors. Therefore, it is important to understand and quantitatively describe the mechanisms leading to formation of fouling deposits. In this work, a CFD model for the radical polymerization of N-vinylpyrrolidone is presented, where the reaction kinetics, a viscosity model, and a transport model for polymer moments are determined from independent experiments. The model is compared to experimental obtained residence time distributions in capillary reactors over a wide range of concentrations. Model predictions are in good agreement with experimental findings.
  • Thumbnail Image
    ItemOpen Access
    Modeling strategies for the propagation of terminal double bonds during the polymerization of N‐vinylpyrrolidone and experimental validation
    (2020) Zander, Christian; Hungenberg, Klaus‐Dieter; Schall, Thomas; Schwede, Christian; Nieken, Ulrich
    Based on a recently suggested reaction mechanism, which involves the production and propagation of terminal double bonds (TDBs), kinetic models for the polymerization of N‐vinylpyrrolidone in aqueous solution are developed. Two modeling strategies, the classes and the pseudodistribution approach, are applied to handle the multidimensional property distributions that result from this reaction mechanism and to get detailed structural property information, e.g., on the chain length distribution and the distribution of TDBs. The structural property information is then used to develop reduced models with significantly lower computational effort, which can be used for process design, on‐line applications or coupled to computational fluid dynamic simulations. To validate the derivations, the models are first compared against each other and finally to experimental results from a continuous stirred tank reactor. The evolution of monomer conversion and molecular weight average data as well as molecular weight distributions can be represented very well by the models that are derived in this article. These results support the correctness of the reaction mechanism predicted by quantum mechanical simulations.